The present invention is directed to an acoustically enhanced carpet system and more specifically to a low mass acoustically enhanced carpet system for the automobile industry and a method of forming the same.
In the automotive market there are a variety of factors and trends that are critical to manufacturers as a result of consumer demand. This leads to focused research and development into these areas. One such consideration is comfort. Comfort is one of the forefront factors that are identified by consumers as being important in their consideration of one vehicle over another. The general term “comfort” comprises many different factors some of which are the usual factors, such as seat comfort, but some less obvious factors are now becoming more important to consumers and hence to the automobile companies and suppliers. One such consideration that is gaining in importance is the acoustic performance of the vehicle and as such ways to dampen the noise within the vehicle compartment that is often caused by outside noises such as road noise, engine noise, vibrations, etc is desirable.
Various acoustical materials are also used to reduce the noise within a vehicle compartment by acoustical absorption. These materials are used in dashboards, wheel wells, trunk compartments, under hoods, headliners, and especially carpeting floor panels. Unfortunately, the acoustic properties of the carpeting floor panels are not the only considerations or functionality taken into account with respect to the carpeting panels because it is necessary to consider other factors such as the cost and weight of the carpeting.
The automotive industry standard for floor carpets world-wide consists of two primary constructions to address interior vehicle acoustics. With reference to FIG. 1A, construction of a first floor carpet system 10 consists of a heavy mass floor system 12, including a tufted nylon/needle punch non-woven carpet 14 that is back-coated with a heavy layer 16 of PVC (polyvinyl chloride), EVA (ethylene vinyl acetate), or PE (polyethylene). A “heavy layer” is defined as a back coating with an application great enough to create an acoustic barrier. The back coating application can usually range from 400-800 g/sq m.
The “heavy layer” 16 acts as a barrier preventing any vehicle air or structure borne noises from entering into the vehicle cabin through the flooring system. Directly beneath the barrier layer is an additional insulator pad 18 which acts as a de-coupler between the carpet system 10 and the vehicle body. This type of carpet system 10 can be a highly effective acoustic solution, but adds significant cost and weight to the vehicle. The “mass backed” carpet systems have limited ability to address specific air borne noise issues in the vehicles interior since it relies on the carpet “face weight” to provide most of the floor's acoustical absorption.
With reference to FIG. 1B, construction of a second floor carpet system 20 consists of a lightweight porous floor system 22 generally formed of a tufted nylon or needle punch non-woven carpet 24 that is applied with a lightweight back coating of latex or PE 26 which is porous enough to allow sound transmissibility through it. Directly beneath this floor carpet construction usually consists of a dual layer/dual density fiber system 28 consisting of a thinly compressed layer and highly lofted resonated/synthetic fiber sandwich as shown or a single layer of highly lofted synthetic fiber (cross or vertically lapped) (not shown). The function of both of these types of constructions is to provide an acoustic system which absorbs noises entering or already in the interior vehicle cabin rather than keeping noise out. The benefits of this type of system are lower vehicle weight and cost, but these types of systems are more sensitive to water intrusion and microbial issues such as mold and mildew.
The light weight porous flooring systems 20 vary in acoustical performance. A dual density/dual layer system provides better lower frequency absorption than conventional heavy layer/mass backed carpet systems but do not perform as well at higher frequencies. Single layer highly lofted fiber (cross or vertically lapped) systems do not provide as much sound absorption at lower frequencies as dual/density but have excellent higher frequency absorption.
Traditional vehicle “sound mapping” has highlighted that most vehicle interior noises radiating from the floor, foot-well and tunnel areas are concentrated in the lower to mid frequency ranges (800 to 2000 Hz). This frequency range is especially difficult to address with acoustic attenuation for either the currently established heavy layer or lightweight porous flooring systems. The lack of acoustical performance in the 800-2000 Hz frequency range is characteristic of most synthetic fibers (PE, PP, PET & Nylon).
Therefore there it is desired in the art to have a low weight, low density carpet application that attains acoustical performance at all ranges while remaining a cost effective solution. It is also desired to have a carpet system that resists water absorption/pass-through and is comprised of recycled materials. These and other problems are overcome by the following novel disclosure.